Floating evaporator saturated suction temperature systems and methods

Abstract

Systems and methods are provided and include first and second case controllers for first and second refrigeration cases. The first case controller receives a first air temperature value of the first refrigeration case and communicates the first air temperature value to the second case controller. The second case controller receives a second air temperature value, determine an evaporator saturated suction temperature (SST) value, controls an evaporator pressure regulator based on a comparison of the evaporator SST value with an evaporator SST setpoint, determines an air temperature control value, determines whether the air temperature control value is within a predetermined range of an air temperature setpoint, and adjusts the evaporator SST setpoint in response to the air temperature control value being outside of the predetermined range of the air temperature setpoint.

What is claimed is: 
     
       1. A system comprising:
 a first case controller for a first refrigeration case having a first evaporator of at least one of a refrigeration system and an HVAC system; and 
 a second case controller for a second refrigeration case having a second evaporator of the at least one of the refrigeration system and the HVAC system; 
 the first refrigeration case and the second refrigeration case discharging refrigerant to an evaporator pressure regulator of the refrigeration system; 
 the first case controller being configured to receive a first air temperature value from a first air temperature sensor associated with the first refrigeration case and to communicate the first air temperature value to the second case controller; 
 the second case controller being configured to: (i) receive a second air temperature value from a second air temperature sensor; (ii) determine an evaporator saturated suction temperature (SST) value based on at least one a first evaporator SST of the first evaporator and a second evaporator SST of the second evaporator; (iii) control the evaporator pressure regulator of the refrigeration system based on a comparison of the evaporator SST value with an evaporator SST setpoint; (iv) determine an air temperature control value based on the first air temperature value and the second air temperature value; (v) determine whether the air temperature control value is within a predetermined range of an air temperature setpoint; and (vi) adjust the evaporator SST setpoint in response to the air temperature control value being outside of the predetermined range of the air temperature setpoint; 
 wherein the second case controller is further configured to increase the SST setpoint in response to the air temperature control value being outside of the predetermined range and below the air temperature setpoint and to decrease the SST setpoint in response to the air temperature control value being outside of the predetermined range and above the air temperature setpoint. 
 
     
     
       2. The system of  claim 1 , wherein the second case controller is further configured to determine the air temperature control value by averaging the first air temperature value and the second air temperature value. 
     
     
       3. The system of  claim 1 , wherein:
 the first case controller is further configured to receive a first evaporator suction pressure from a first evaporator suction pressure sensor associated with the first evaporator and to communicate the first evaporator suction pressure to the second case controller; 
 the second case controller is further configured to: (i) receive a second evaporator suction pressure from a second evaporator suction pressure sensor associated with the second evaporator; (ii) determine the evaporator SST value based on the first evaporator suction pressure and the second evaporator suction pressure; (iii) compare the evaporator SST value with the evaporator SST setpoint; and (iv) control the evaporator pressure regulator based on the comparison of the evaporator SST value with the evaporator SST setpoint. 
 
     
     
       4. A method comprising:
 receiving, with a first case controller for a first refrigeration case having a first evaporator of at least one of a refrigeration system and an HVAC system, a first air temperature value from a first air temperature sensor associated with the first refrigeration case; 
 communicating, with the first case controller, the first air temperature value to a second case controller for a second refrigeration case having a second evaporator of the at least one of the refrigeration system and the HVAC system, the first refrigeration case and the second refrigeration case discharging refrigerant to an evaporator pressure regulator of the refrigeration system; 
 receiving, with the second case controller, a second air temperature value from a second air temperature sensor; 
 determining, with the second case controller, an evaporator saturated suction temperature (SST) value based on at least one a first evaporator SST of the first evaporator and a second evaporator SST of the second evaporator; 
 controlling, with the second case controller, the evaporator pressure regulator of the refrigeration system based on a comparison of the evaporator SST value with an evaporator SST setpoint; 
 determining, with the second case controller, an air temperature control value based on the first air temperature value and the second air temperature value; 
 determining, with the second case controller, whether the air temperature control value is within a predetermined range of an air temperature setpoint; 
 adjusting, with the second case controller, the evaporator SST setpoint in response to the air temperature control value being outside of the predetermined range of the air temperature setpoint; 
 increasing, with the second case controller, the SST setpoint in response to the air temperature control value being outside of the predetermined range and below the air temperature setpoint; and 
 decreasing, with the second case controller, the SST setpoint in response to the air temperature control value being outside of the predetermined range and above the air temperature setpoint. 
 
     
     
       5. The method of  claim 4 , further comprising determining, with the second case controller, the air temperature control value by averaging the first air temperature value and the second air temperature value. 
     
     
       6. The method of  claim 4 , further comprising:
 receiving, with the first case controller, a first evaporator suction pressure from a first evaporator suction pressure sensor associated with the first evaporator; 
 communicating, with the first case controller, the first evaporator suction pressure to the second case controller; 
 receiving, with the second case controller, a second evaporator suction pressure from a second evaporator suction pressure sensor associated with the second evaporator; 
 determining, with the second case controller, the evaporator SST value based on the first evaporator suction pressure and the second evaporator suction pressure; 
 comparing, with the second case controller, the evaporator SST value with the evaporator SST setpoint; and 
 controlling, with the second case controller, the evaporator pressure regulator based on the comparison of the evaporator SST value with the evaporator SST setpoint. 
 
     
     
       7. A system comprising:
 a first case controller for a first refrigeration case having a first evaporator of at least one of a refrigeration system and an HVAC system; and 
 a second case controller for a second refrigeration case having a second evaporator of the at least one of the refrigeration system and the HVAC system; 
 the first refrigeration case and the second refrigeration case discharging refrigerant to an evaporator pressure regulator of the refrigeration system; 
 the first case controller being configured to receive a first air temperature value from a first air temperature sensor associated with the first refrigeration case and to communicate the first air temperature value to the second case controller; 
 the second case controller being configured to: (i) receive a second air temperature value from a second air temperature sensor; (ii) determine an evaporator saturated suction temperature (SST) value based on at least one a first evaporator SST of the first evaporator and a second evaporator SST of the second evaporator; (iii) control the evaporator pressure regulator of the refrigeration system based on a comparison of the evaporator SST value with an evaporator SST setpoint; (iv) determine an air temperature control value based on the first air temperature value and the second air temperature value; (v) determine whether the air temperature control value is within a predetermined range of an air temperature setpoint; and (vi) adjust the evaporator SST setpoint in response to the air temperature control value being outside of the predetermined range of the air temperature setpoint; 
 wherein: 
 the first case controller is further configured to receive a first evaporator suction pressure from a first evaporator suction pressure sensor associated with the first evaporator and to communicate the first evaporator suction pressure to the second case controller; and 
 the second case controller is further configured to: (i) receive a second evaporator suction pressure from a second evaporator suction pressure sensor associated with the second evaporator; (ii) determine the evaporator SST value based on the first evaporator suction pressure and the second evaporator suction pressure; (iii) compare the evaporator SST value with the evaporator SST setpoint; and (iv) control the evaporator pressure regulator based on the comparison of the evaporator SST value with the evaporator SST setpoint. 
 
     
     
       8. The system of  claim 7 , wherein the second case controller is further configured to determine the air temperature control value by averaging the first air temperature value and the second air temperature value. 
     
     
       9. The system of  claim 7 , wherein the second case controller is further configured to increase the SST setpoint in response to the air temperature control value being outside of the predetermined range and below the air temperature setpoint and to decrease the SST setpoint in response to the air temperature control value being outside of the predetermined range and above the air temperature setpoint.